The human body performs millions of chemical reactions, collectively known as metabolism. For example, the process by which food (and liquids) gets converted into energy is called metabolism. These functions help us stay alive and function and help the body to grow and repair tissues. It also enables regular functioning by breaking down the nutrients from the diet.

Metabolism greatly impacts how many calories the body burns at any given time, which is essential for weight gain, loss, or maintenance. It is because metabolism maintains a balance between the energy in and the energy out. Similarly, basal metabolic rate (BMR) is the amount of energy burned only to keep the body operating while at rest. It makes up most of the metabolism and accounts for between 50 and 80% of the energy required. 

Good metabolic health aids in removing toxins from the body and can improve blood circulation, making a person feel more energised. Furthermore, it enhances mood and provides internal energy for work, increasing immunity, assisting in rapid weight loss, and improving sleep quality. Irritable bowel syndrome, diarrhoea, or frequent constipation are common problems caused by poor metabolism. Also, they are one of the significant problems associated with poor metabolic health. In addition, you should consult a nutritionist if you are experiencing any of these symptoms. Several tests can assess poor metabolic health.

A HealthifyPro 2.0 subscription includes an extensive panel of 80 parameters in a single blood test performed in the comfort of your own home. Also, continuous glucose monitoring allows you to assess the appropriate food and activity levels to maintain your metabolic health. The convenience of being able to consult with a nutritionist always makes food selection extremely practical. As a result, your metabolic health improves with correct dietary interventions, and you can achieve sustainable weight loss.

The HealthifyMe Note

Metabolic health is critical to an individual’s well-being. Unfortunately, poor metabolic health can lead to heart disease, diabetes, stroke, and kidney and liver disease. Metabolic disorders can impair an individual’s ability to metabolise essential nutrients and enzymes. Furthermore, it interferes with the biochemical reactions required for synthesising critical micronutrients such as protein and carbohydrates. The first sign of poor metabolic health is usually being overweight and having a sluggish metabolism. Therefore, please get a health check-up done if you cannot lose weight or face sleep irregularities, difficulty concentrating or feeling stressed. 


The Basal Metabolic Rate (BMR) is higher in infants and young children, peaking between ages 3 and 5. The basal metabolism of newborn infants is roughly 25 calories per hour per square metre of the body surface. It reaches a peak of slightly more than 50 calories per hour per square metre of body surface between the ages of 3 and 5, then gradually declines throughout childhood, middle life, and old age.

People’s metabolism slows down as they age due to sarcopenia, a natural loss of muscle tissue, and hormonal and neurological abnormalities. After the age of 30, the loss of lean muscle mass causes a 3-5% decline in BMR every decade. But the good news is that regular resistance and strength training can slow or stop muscle loss, eventually assisting in a metabolic rate reduction.


The genes may play a role in determining the rate of metabolism. As a result, the BMR rates differ between families. In some cases, a faulty gene produces a protein inefficiently processing food, resulting in a metabolic disorder. Most hereditary metabolic disorders get treated with intensive dietary monitoring and medical supervision.


Men often have a higher metabolic rate than women. It is because women typically have a higher body fat percentage and less muscle mass than men of comparable size. According to a study, women’s basal metabolic rate is typically 5–10% lower than men’s.

Body Size

The metabolic rate increases when your body mass, height, and surface area increase. Because larger bodies have more metabolising tissue, larger organs, and more fluid volume to maintain, the BMR is higher. For example, a man of 6’6″ height has a different metabolism than a man of 5’6″.

Muscle Mass

Fat tissue has a lower metabolic activity than muscle tissue. Therefore, it burns far fewer calories than most other human tissues and organs. According to a study, metabolism increases as lean or muscle mass increases (since your bones, organs, skin, brain, etc., usually remain the same). Having more muscle mass corresponds to having a higher metabolic rate. Therefore, the greater one’s muscle mass, the more calories one burns daily.

Hormonal Factors

The hormonal system manages the metabolic rate. Because hormones control metabolism, hormonal imbalances can affect how quickly or slowly the body burns energy.

A study shows that the thyroid gland gets linked to the most common hormonal conditions. Also, the thyroid gland secretes hormones that control metabolic processes (including the rate at which calories get burned; energy expenditure).

Thyroid conditions consist of: 

Hypothyroidism (underactive thyroid)

  • Because the thyroid gland doesn’t release enough hormones, metabolism slows.
  • Autoimmune disease is a frequent cause. Hashimoto’s syndrome
  • Symptoms include constipation, unexpected weight gain, fatigue, despair, and sadness.

Hyperthyroidism (overactive thyroid)

  • The gland releases more hormones than necessary.
  • Graves disease is a common cause.
  • Symptoms include increased appetite, weight loss, anxiety, and diarrhoea.

Thyroxin, made by the thyroid gland, is a crucial basal metabolic rate (BMR) regulator that increases metabolic activity in the body. The BMR increases as thyroxin production increases. Thyrotoxicosis is a disease in which the body produces too much thyroxin, causing BMR to double. Conversely, Myxoedema occurs when insufficient thyroxin production can cause BMR to fall to 30-40% of normal. 

Physical Activity

According to a study, muscle energy expenditure accounts for about 20% of total energy expenditure when at rest. However, when people work out hard, their energy consumption can increase by 50 times or more. During vigorous physical activity, muscles can burn up to 717 calories per hour.

The amount of energy expended during a workout varies depending on the individual and intensity of the session, including the person’s body type, age, state of health, and level of exercise. Regular exercise trains the body to burn calories more quickly even when at rest and develops muscular mass, thereby enhancing metabolism.

Environmental Temperature

The body has to work harder to maintain an average body temperature in extreme cold or heat, which speeds up the metabolism. As per studies, people who live in tropical climates frequently have higher BMRs than those in temperate climates. It is because the body requires energy to maintain a constant temperature.

Body Temperature

The body’s metabolic rate (BMR) rises by about 7% for every 0.5°C increase in internal temperature. Also, higher temperatures speed up chemical reactions in the body. So, a patient with a fever of 42° C (roughly 4° C above normal) would experience an increase in BMR of about 50%.

A study indicated that fever raises body temperature, which increases the body’s metabolic rate (BMR) by 14–15% per degree Celsius. The body’s accelerated metabolic processes undoubtedly bring on this increase.


The metabolism remains stable with enough sleep. Poor sleep disrupts the body’s natural sleep cycle, which affects hormones and makes it more difficult for the body to utilise energy efficiently. A sluggish metabolism and unhealthy food cravings may result from poor sleep.


Metabolism can get accelerated by certain substances, such as nicotine or caffeine. In addition, regardless of what one eats, some medications, such as antidepressants and steroids, can cause weight gain by slowing the metabolism.


The basal metabolic rate rises while one is unwell because the body has to work harder to regenerate tissues and create an immunological response. As per research, fever, illness, or injury may cause a twofold rise in BMR.


The body produces cortisol hormone in response to stress. If the stress levels are high, the body gets engaged in a “fight or flight” reaction, which causes it to continue producing more cortisol. 

Insulin, an anabolic hormone, is one of the key hormones in fat metabolism. However, the body faces difficulty using insulin due to high cortisol levels. Also, the improper use of insulin prevents the body from metabolising fat and retaining fat, which slows metabolism and causes weight gain.

Weight gain and long-term fat storage are both correlated with chronic stress. According to a study, having one or more stressful experiences before consuming a single high-fat meal can slow down metabolism. As a result, it can reduce the body’s metabolism and result in weight gain. The subjects also had higher insulin levels, which contributed to fat storage. 

Overtraining, excessive exercise, and undereating to repair or undersleep for adequate recovery are all symptoms of stress. When the body gets pushed too far, the hormones may become out of balance, causing the body to become inflammatory, stressed, and disrupting the metabolism.

Nutrient Deficiencies

Some nutrients may impact metabolism. A diet lacking in iodine, for instance, decreases thyroid function and lowers metabolism. More significant calcium and vitamin D intake, taken with magnesium for better absorption, are associated with healthier bones and a better system for controlling body fat and metabolism. Having too little iron in the body can slow down metabolism.


Water aids in the metabolism of food; therefore, staying hydrated is essential for maintaining an effective metabolism. According to a study, consuming 500 mL of water raised metabolic rate by 30%, with the increase beginning within 10 minutes and peaking between 30 and 40 minutes. It is brought on by water-induced thermogenesis, in which water stimulates metabolism.

Thirst is often confused with hunger; drinking extra water can help reduce overeating. On the other hand, the metabolism may slow down if one doesn’t drink enough water. Moreover, alcohol impacts the liver’s processing and can delay metabolism, while sugary drinks can cause insulin resistance.


Your food choices and portion control have a significant impact on your metabolism. Food has a thermic effect, which causes the metabolism to increase after eating due to the energy required to consume, digest, and metabolise food. The rate of metabolism increases shortly after one begins eating and peaks approximately 2-3 hours later. This rate can range from 2-30%, depending on the portion and quality of the meal. The degree to which various foods raise metabolism varies. For example, foods that are hot and spicy have a thermic effect. 

Eating too few calories causes the body to decrease its metabolism to conserve energy (as does crash dieting, extreme diets, and starvation). Eating less when one wants to lose weight can backfire since the body will hold onto those more calories, making it more challenging to shed the extra pounds.

Intermittent fasting has recently gained popularity and benefits metabolism and metabolic health due to its association with an increase in the balance of essential hormones involved in fat metabolism (insulin, human growth hormone, and norepinephrine). These hormones influence a person’s weight, food consumption, and calorie expenditure. As a result, fasting can help with fat burning and weight loss.

The HealthifyMe Note

The essential factors affecting metabolism include age, gender, stress, genetics, body size, muscle mass, hormonal and environmental factors, and many more. In addition, nutrition and physical activity are key factors affecting metabolism. For good health, adequate sleep and hydration are necessary.


Metabolism is the process of generating energy from food to work efficiently. Diabetes, obesity, and cardiovascular disease are all examples of metabolic diseases. Also, normal blood pressure, blood sugar, and cholesterol levels improve an individual’s metabolic health. On the other hand, age, gender, genetics, diet, stress, hydration, and other factors affect metabolism. Furthermore, being overweight or obese can be an essential indicator signifying poor metabolic health. 

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